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Abstract The effects of environmental and conservation management scenarios on the permanence of the historical book collections housed at the Classense Library (Ravenna, Italy) were investigated. Non-destructive material surveys delivered paper pH and degree of polymerisation data that, in conjunction with the Collections Demography dose–response function, provide heritage managers with estimations of the predicted collection lifetimes in diverse environmental management scenarios. For the first time, quantitative measurements of paper properties obtained in a historical library collection were used to elaborate isochrone and demographic plots, evaluated against the long-term planning horizon of 500 years. The scenarios include preventive and interventive actions aiming to preserve the fitness-for-use of collection items in terms of their ability to withstand manual handling, and consider cooling, dehumidification and deacidification, as well as combinations thereof. The results inform the conservation decision-makers about the preservation outcomes of environmental management options, to be considered for further action, once environmental, economic and social sustainability of such scenarios is considered.

Abstract An innovative survey was conducted of the collections of the historical Biblioteca Classense, located in the urban area of Ravenna (Northern Italy). The survey aimed to evaluate the current conservation state of the book collections, where 297 paper-based items, including incunabula, manuscripts and books, dating from the 14th to the 20th century, were selected for analysis. This innovative survey was carried out non-destructively by assessing degradation visually and by measuring NIR spectral data followed by multivariate data analysis. Chemical and physical paper properties, important for paper characterisation and implementation of conservation strategies were determined, including paper type, pH, degree of polymerisation (DP), tensile strength, lignin, protein, and rosin content. This survey provided a significant quantitative dataset for rag paper covering a 600-year period. The analysis of DP changes over time allowed the first experimental estimation of the rate constant for historical rag paper, i.e., (4.2 ± 0.6)·10−7 year−1, which was validated with predictions based on the Collections Demography dose response function for historic paper taking into account the past climate in Ravenna. Statistical methods were employed to describe the correlations between the measured variables and different features of the books, suggesting that the degree of polymerisation can be used as a general proxy for rag paper mechanical strength.